I think its too much too, I would definitely query it. I recently had an issue with mine where vet left some extra medication for me which she said I could return and get refunded if not required. If she hadn't of said that I would have said leave it for now because it was expensive. So when it was not required, I sent it back paying £12 postage, fair enough, but then they would only give me a part refund...wasn't impressed at all. They aren't always very fair and it puts us in a difficult position because the last thing you want to do is spoil the relationship with your vet.
I've been buying vetwrap recently, the Vet said they could supply it but it'd be cheaper if i bought it elsewhere and I managed to get it for 1.99 or 3 for 2 at Mole Valley Farmers. The vets did give me some manuka honey dressings for free though, as they were about to go out of date..
I called a vet out to check if a mare was in foal (internal exam as she would have been about 6 months) vet said yes then no then yes, then said she would get her boss out to check, he came checked and said no. Bill arrived for two call outs and two exams, I refused to pay and told them next time send a vet that knew what she was doing ... they did halve the bill
I was charged £11 for a TINY bit of hibiscrub by a small animal vet last month. It was probably around 20ml worth - unfortunately I didn't realise they were prescribing hibiscrub because I have lots at home for the horses. Lesson learnt, will definitely ask next time.
OP that is a lot. A markup is fair, I wouldn't begrudge them a fiver too much, but that is taking the mickey rather.